Export ActiveRecord Tables to CSV

exporter.rb

require 'csv'

module Exporter
  DEFAULT_EXPORT_TABLES = [ Invoice, InvoiceItem, Item, Merchant, Transaction, User ]
  DESTINATION_FOLDER = "tmp/"

  def self.included(klass)
    klass.extend ClassLevelMethods
  end

  def self.export_tables_to_csv(tables = DEFAULT_EXPORT_TABLES)
    tables.each do |klass|
      klass.send(:include, self)
      klass.export_table_to_csv
    end
  end

  def data
    self.class.column_names.map { |column| send(column) }
  end

  module ClassLevelMethods
    def export_table_to_csv
      CSV.open(filename_for_class, "w") do |output_file|
        output_file << column_names
        data.each{ |row| output_file << row }
      end
    end

    def filename_for_class
      [DESTINATION_FOLDER, to_s.pluralize.underscore, '.csv'].join
    end

    def data
      all.map(&:data)
    end
  end
end

I chose not to change Jeff's original name on the "tables" variable. Probably better named "models".

activesupport would be required implicitly since we're assuming active record models here. We could also do find_in_batches. My changes were almost entirely stylistic. Ultimately the best approach is to mysql the database's dump utility for any of this :)

(^_-) very true. This code could also work with other ORMs tho but granted using an ORM for that task seems totally overkill.

Yup, that's why there are task-oriented gems like Taps around.